diff mbox

[v2,1/5] tpm: fix potential buffer overruns caused by bit glitches on the bus

Message ID 1518121688.21828.12.camel@HansenPartnership.com (mailing list archive)
State New, archived
Headers show

Commit Message

James Bottomley Feb. 8, 2018, 8:28 p.m. UTC 
From: Jeremy Boone <jeremy.boone@nccgroup.trust>

Discrete TPMs are often connected over slow serial buses which, on
some platforms, can have glitches causing bit flips.  If a bit does
flip it could cause an overrun if it's in one of the size parameters,
so sanity check that we're not overrunning the provided buffer when
doing a memcpy().

Signed-off-by: Jeremy Boone <jeremy.boone@nccgroup.trust>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
v2: add -EFAULT for received being too big

 drivers/char/tpm/tpm-interface.c | 4 ++++
 drivers/char/tpm/tpm2-cmd.c      | 4 ++++
 2 files changed, 8 insertions(+)

Comments

Jarkko Sakkinen Feb. 9, 2018, 4:44 p.m. UTC | #1 
On Thu, Feb 08, 2018 at 12:28:08PM -0800, James Bottomley wrote:
> From: Jeremy Boone <jeremy.boone@nccgroup.trust>
> 
> Discrete TPMs are often connected over slow serial buses which, on
> some platforms, can have glitches causing bit flips.  If a bit does
> flip it could cause an overrun if it's in one of the size parameters,
> so sanity check that we're not overrunning the provided buffer when
> doing a memcpy().
> 
> Signed-off-by: Jeremy Boone <jeremy.boone@nccgroup.trust>
> Cc: stable@vger.kernel.org
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

/Jarkko
diff mbox

Patch

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1d6729be4cd6..3cec403a80b3 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1228,6 +1228,10 @@  int tpm_get_random(u32 chip_num, u8 *out, size_t max)
 			break;
 
 		recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
+		if (recd > num_bytes) {
+			total = -EFAULT;
+			break;
+		}
 
 		rlength = be32_to_cpu(tpm_cmd.header.out.length);
 		if (rlength < offsetof(struct tpm_getrandom_out, rng_data) +
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index f40d20671a78..f6be08483ae6 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -683,6 +683,10 @@  static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	if (!rc) {
 		data_len = be16_to_cpup(
 			(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
+		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE + 1) {
+			rc = -EFAULT;
+			goto out;
+		}
 
 		rlength = be32_to_cpu(((struct tpm2_cmd *)&buf)
 					->header.out.length);